JP5636557B2 - Infrared sensor manufacturing method, infrared sensor, and quantum infrared gas concentration meter - Google Patents

Description

  The present invention relates to an infrared sensor manufacturing method, an infrared sensor, and a quantum infrared gas concentration meter, and more specifically, an infrared sensor manufacturing method for forming an optical filter on a light receiving surface of a sensor element, an infrared sensor, and a quantum infrared gas. Concentration meter.

  In general, an infrared sensor is used for detecting an object such as a human body and measuring various gas concentrations in the atmosphere. This type of conventional infrared sensor includes a package having a recess formed on the top surface, an infrared sensor element mounted on the bottom surface of the recess, and an ultraviolet curable resin attached around the recess on the top surface of the package. An infrared sensor including a plate-like optical filter formed has been proposed. This infrared sensor can improve the adhesive strength between the optical filter and the package, and can provide a small-sized and highly reliable infrared sensor including an optical filter that can be manufactured at low cost. It is said that.

  However, the infrared sensor as described above 1) Since the outer peripheral portion of the light receiving surface of an expensive optical filter is bonded to the package, a portion that does not function as an optical filter is required, resulting in an increase in cost. When applied to infrared sensors used in human body detection or security equipment, for example, due to variations in application amount and application state, poor adhesion, and adhesive oozing out of areas other than the adhesive part, the detection range becomes narrower. There is a problem that the visual field characteristics vary.

  In order to solve these problems, for example, an infrared sensor as described in Patent Document 1 has been proposed. The one described in Patent Document 1 has a function of causing the infrared sensor element to receive infrared light of a predetermined wavelength in the opening of the package containing the infrared sensor element, and a function as a lid for sealing the opening of the package. The present invention relates to an infrared sensor having a structure in which an optical filter that simultaneously performs is disposed and a method for manufacturing the same. That is, as a package, a support portion that supports the optical filter at a position lower than the upper end portion of the peripheral wall of the package, a side surface of the optical filter supported by the support portion, and a gap formed between the peripheral wall of the package Using a package with a recess that communicates, with the optical filter supported by the support, supply adhesive to the recess, and allow the adhesive to penetrate into the gap between the optical filter and the peripheral wall of the package by capillary action. The optical filter is fixed to the opening of the package via an adhesive.

  As an infrared sensor in which an infrared sensor element and an optical filter are packaged and integrated, for example, there is one disclosed in Patent Document 2. The one disclosed in Patent Document 2 is formed by supporting an infrared sensor unit using a thermopile or the like on a surface of a silicon substrate on the diaphragm on one side of the front and back surfaces of the silicon substrate, and the other side. In addition, an optical filter for selecting a received wavelength comprising an optical interference multilayer is formed.

  Regarding an infrared sensor in which an optical filter corresponding to a detection element and selecting and transmitting only light of a predetermined wavelength band by an optical thin film is disposed between a window material that transmits light such as infrared rays and the detection element. For example, it is disclosed in Patent Document 3.

  In addition, the resonance emission spectrum of carbon dioxide in the flame has a peak at 4.3 μm, and it is possible to detect fire with high accuracy by comparing it with the infrared intensity of the band for comparing other emission. Known from document 4.

Conventional infrared sensors are classified into thermal infrared sensors and quantum infrared sensors. A thermal infrared sensor is a sensor that uses infrared energy as heat, and the temperature of the sensor itself rises due to the infrared thermal energy, and the effects (resistance change, capacitance change, electromotive force, spontaneous polarization) due to the temperature rise. An element that converts an electrical signal. This thermal infrared sensor includes pyroelectric type (PZT, LiTaO ₃ ), thermoelectromotive force type (thermopile, thermocouple), and conductive type (bolometer, thermistor), sensitivity does not depend on wavelength, and cooling is unnecessary. It is. Moreover, the response speed is slow and the detection capability is not so high. Further, since it is necessary to thermally separate the infrared detection portion and the peripheral portion, it is necessary to provide a gap between the infrared detection portion and the peripheral portion, and the above-described optical filter cannot be bonded to the infrared detection portion.

  On the other hand, a quantum infrared sensor is a sensor that uses electrons and holes generated by photons when an infrared ray is irradiated on a semiconductor. Photoconductive types (such as HgCdTe) and photovoltaic types (such as InAs) are available. is there. This quantum infrared sensor has the characteristics that the sensitivity depends on the wavelength, has high sensitivity, and has a high response speed. However, it needs to be cooled, and it is generally used with cooling mechanisms such as Peltier elements and Stirling coolers. It was the target.

JP 2007-288168 A JP 2006-058203 A JP 2002-243544 A JP 2001-249047 A

  In such a conventional infrared sensor element, in order to cope with the significant change in the sensor temperature described above, a can package is used to provide a gap around the sensor element and further evacuate or use a gas having low thermal conductivity. A method has been adopted in which this phenomenon can be alleviated by filling or attaching a heat sink part having a large heat capacity to thermally shut off and stabilize the detection part. However, in these configurations, the shape of the element is complicated, increased in size, and increased in weight, and the package is required to have high working accuracy, which increases the cost.

  In addition, it has been proposed to use a package such as a mold resin without using a can package, or to attach a filter directly on the surface of the infrared element. In these cases, a thermal infrared sensor element is also proposed. However, there is a problem in that stable measurement cannot be performed when the temperature or flow rate of the gas to be measured changes significantly due to insufficient thermal separation.

  In addition, when a conventional quantum infrared sensor is used, high sensitivity cannot be obtained stably at room temperature. Therefore, a method of thermally stabilizing the element with a large heat sink, a Peltier element, or liquid nitrogen A method of cooling is performed. In order to prevent dew condensation due to cooling of the element and to enclose with a gas having low thermal conductivity such as Xe or Ne in order to suppress heat conduction to the outside, a can package is formed like a thermal infrared sensor. used. For this reason, there has been a problem that the cost is increased in order to increase the size and complexity of the element and to require high working accuracy for the package.

  The present invention has been made in view of such problems, and its object is to have a small and simple sensor shape and to be stable against disturbance changes such as changes in the flow rate and temperature of the measurement gas. It is an object of the present invention to provide an infrared sensor manufacturing method, an infrared sensor, and a quantum infrared gas concentration meter that can be measured in this manner.

The present invention has been made in order to achieve such an object, and one aspect of the present invention is the second of the wafer facing the first main surface of the wafer on which a plurality of quantum sensor elements are formed. A filtering step of attaching an optical filter to the entire main surface of the quantum sensor element through an adhesive formed on the periphery avoiding the infrared absorbing portion of the quantum sensor element, and separating the wafer into a plurality of the quantum types a first dicing step of forming a sensor element, the quantum type sensor elements, separated by the first dicing step, in a recess formed in the lead frame and the supporting substrate, a first of said wafer major surface is exposed, the die bonding step of the optical filter is mounted in contact with the supporting substrate, a first formed on a main surface quantum type sensor elements of said wafer and said lead frame to wire Ri and wire bonding step of receiving connection in said recess, and a molding step of molding at front Ki凹 portion except for the second optical filter surface formed on the main surface of the wafer resin, the quantum type sensor element And a second dicing step for separating the lead frame into pieces, and the sensor element and the optical filter are integrally formed. Is the method. Example 1
In another aspect of the present invention, the lead frame has a step portion on a side surface of the lead frame forming the recess, and the wire bonding step is performed on the quantum surface formed on the first main surface of the wafer. In the infrared sensor manufacturing method, the mold sensor element and the stepped portion of the lead frame are housed and connected in the recess by a wire.

Another aspect of the present invention is an infrared sensor manufactured by the above-described method for manufacturing an infrared sensor. (Example 2)

Another aspect of the present invention is that an infrared light source is arranged at one end in a sample cell that constitutes a flow path of a gas to be measured, and the infrared sensor is arranged at the other end in the sample cell. It is a featured quantum infrared gas concentration meter. Example 3

  According to the present invention, the first dicing process for separating the wafer to form the plurality of sensor elements, and the sensor elements separated by the first dicing process are mounted on the lead frame and resin-molded together with the wires. The second dicing step for separating the sensor element and the lead frame into individual pieces, and the filtering step for forming an optical filter on the light receiving surface of the sensor element in the previous stage of the first or second dicing step, are small and An infrared sensor manufacturing method, an infrared sensor, and a quantum infrared gas concentration meter having a simple sensor shape and capable of stably measuring changes in disturbance such as a change in flow rate and temperature of a measurement gas It is possible to provide.

(A) thru | or (c) are process drawings (the 1) for demonstrating Example 1 of the manufacturing method of the infrared sensor of this invention. (A) thru | or (c) are process drawings (the 2) for demonstrating Example 1 of the manufacturing method of the infrared sensor of this invention. (A) thru | or (c) are process drawings (the 1) for demonstrating Example 2 of the manufacturing method of the infrared sensor of this invention. (A) thru | or (d) are process drawings (the 2) for demonstrating Example 2 of the manufacturing method of the infrared sensor of this invention. It is a figure which shows the sensitivity spectrum of the infrared sensor for demonstrating the quantum type infrared gas concentration meter (Example 3) using the infrared sensor of this invention. It is a figure which shows the various gas infrared transmission spectrums of the sensor sensitivity range for demonstrating the quantum type infrared gas concentration meter (Example 3) using the infrared sensor of this invention. It is a block diagram in order to demonstrate the quantum type infrared gas concentration meter (Example 3) which concerns on this invention. By NDIR method for describing a quantum infrared gas concentration meter using the infrared sensor of the present invention (Example 3) is a diagram showing an example of a CO ₂ concentration quantitatively. It is a figure which shows the optical spectrum by the difference in the temperature of a heat generating body for demonstrating the human sensitive sensor (Example 4) using the infrared sensor of this invention. It is the figure which showed the example which resin-molded two wavelengths integrally about the quantum type infrared gas concentration meter (Example 3) using the infrared sensor of this invention. It is the figure which showed the example which resin-molded four wavelengths integrally about the quantum type infrared gas concentration meter (Example 3) using the infrared sensor of this invention. It is a specific block diagram of the quantum type sensor element used for Example 1 of the infrared sensor which concerns on this invention, and each Example mentioned later. 3 is a top view for explaining an adhesive layer of a sensor element unit in Example 1. FIG. FIG. 14 is a top view for explaining an embodiment in which a cutout portion is provided in the adhesive layer shown in FIG. 13, and (a) shows a cutout portion 112 a at an intermediate portion of the adhesive layer on the outer peripheral portion of the infrared absorbing portion 114. The case where it provided is shown, (b) has shown the case where the notch part 112a is provided in the corner part of the contact bonding layer of an outer peripheral part. 10 is a top view for explaining an adhesive layer of a sensor element unit in Example 2. FIG.

Embodiments of the present invention will be described below with reference to the drawings.
<Example 1>
FIGS. 1A to 1C and FIGS. 2A to 2C are process diagrams for explaining Example 1 of the manufacturing method of the infrared sensor of the present invention.

  The manufacturing method of the infrared sensor 18 according to the first embodiment of the present invention is a manufacturing method of the infrared sensor 18 in which the optical filter 12 is formed on the light receiving surface 13a of the sensor element 13, and the wafer 10 with the optical filter 12 is separated. A first dicing process for forming a plurality of sensor elements 13, and the sensor elements 13 separated by the first dicing process are mounted on a lead frame 14, and the sensor elements 13 and leads molded with a resin 17 together with wires 16 A second dicing step for dividing the frame 14 into pieces, and a filtering step for forming the optical filter 12 on the light receiving surface 13a of the sensor element 13 before the first dicing step. 12 is formed directly and integrally.

  First, the optical filter 12 is attached to the back surface of the wafer substrate 11 through an adhesive to form the wafer 10 (FIG. 1A; filtering process). Next, the wafer 10 is separated to form a plurality of sensor elements 13 with optical filters 12 (FIG. 1A; first dicing step). Next, the sensor element 13 separated by the first dicing process is aligned in the recess 15 of the lead frame 14 and mounted so that the light receiving surface 13a of the sensor element 13 faces downward in the recess 15. (FIG. 1 (b); die bonding step). Next, the sensor element 13 and the lead frame 14 accommodated in the recess 15 by the die bonding process are accommodated and connected in the recess 15 by the wire 16 (FIG. 1C; wire bonding process).

  Next, the inside of the recess 15 is molded with the resin 17 except for the light receiving surface 13a of the sensor element 13 to which the wire bonding is performed in this wire bonding process (FIG. 2A; molding process). Next, the sensor element 13 and the lead frame 14 molded with the resin 17 together with the wire 16 are separated into individual pieces (FIG. 2B; second dicing step).

  As described above, the manufacturing method of the infrared sensor according to the first embodiment of the present invention attaches the optical filter 12 to the wafer substrate 11 via the adhesive in the first stage of the first dicing process. 1 (a), a filtering process and a first dicing process, a die bonding process as shown in FIG. 1 (b), a wire bonding process as shown in FIG. 1 (c), and FIG. 2 (a). Through the molding process as shown in FIG. 2 and the second dicing process as shown in FIG. 2B, the infrared sensor 18 as shown in FIG. 2C is completed. That is, in the infrared sensor 18 completed according to the first embodiment, the optical filter 12 is directly provided only on the light receiving surface 13 a of the sensor element 13.

  The optical filter in the filtering process shown in FIG. 1A described above may be any filter having a function of selectively transmitting infrared light. As an example of this optical filter, an optical member and a thin film formed in multiple layers on this optical member have a function of not transmitting infrared rays having a long wavelength, a short wavelength, or both, and these As a result, the optical filter has a function of transmitting only infrared rays having a specific wavelength.

This optical filter may perform a function of transmitting only infrared rays having a specific wavelength, or may use a plurality of sheets depending on circumstances. In addition, as a material of the optical member, a material that transmits predetermined infrared rays such as silicon (Si), glass (SiO ₂ ), sapphire (Al ₂ O ₃ ), Ge, ZnS, ZnSe, CaF ₂ , and BaF ₂ is used. In addition, as a thin film material to be deposited on this, silicon (Si), glass (SiO ₂ ), sapphire (Al ₂ O ₃ ), Ge, ZnS, TiO ₂ , MgF ₂ , SiO ₂ , ZrO ₂ , Ta ₂ O ₅ or the like is used. In addition, the dielectric multilayer filter in which dielectrics having different refractive indexes are laminated in layers on the optical member may be formed on both sides with a predetermined thickness configuration different on the front and back sides, or formed only on one side. May be. Further, for the purpose of preventing unnecessary reflection, an antireflection film may be formed on the front surface, both surfaces on the back surface, or the outermost layer on one surface.

  Examples of the adhesive for attaching the optical filter 12 to the surface of the wafer substrate 11 include polyimide, polyethylene, epoxy, acrylic, and rubber. An adhesive having a transmission band different from that of the optical filter and an absorption band of the adhesive is preferable. The sensor element 13 is preferably a quantum sensor element. This quantum type sensor element is a quantum type sensor element that can detect infrared light transmitted through the optical filter 12 at room temperature, and includes a photovoltaic type, a photoconductive effect type, a photoelectron emission effect type, and the like. Any of these types can be used in the present invention. However, the photoelectron emission effect type requires a special environment such as high vacuum, and there is a problem that the device itself and the sensor element become large. Since the current is passed through the sensor element itself, there is a drawback that noise increases, and it is difficult to measure with high sensitivity at room temperature. Therefore, the photovoltaic type is preferred most preferably.

  In addition, a quantum infrared sensor capable of detecting infrared light transmitted through an optical filter at room temperature has a light receiving portion having a photodiode structure that generates a photovoltaic effect by infrared light on a substrate. As this substrate, a single crystal Si substrate, a glass substrate, a GaAs substrate, or the like can be used. Here, a semi-insulating GaAs substrate is used as an example.

  The sensor element is a quantum sensor element in which the light receiving surface is excited by infrared photons (photons), and the electrical properties of the light receiving surface are changed by this excitation. In this sensor element, infrared energy is converted into electric energy by photoelectric conversion on the light receiving surface. Because of the quantum type, the infrared detection sensitivity of the sensor element is hardly affected by the heat capacity of the sensor element and its surroundings.

  In addition, the light receiving surface of the sensor element is made of, for example, InAsxSb1-x (0 ≦ x ≦ 1) and can efficiently photoelectrically convert infrared rays having a wavelength of about 1 to 11 μm. The sensor element is composed of, for example, an InSb quantum PIN photodiode formed on a semi-insulating GaAs substrate.

  The InSb quantum PIN photodiode is doped with a substrate, an n-type InSb layer (contact layer) formed on the substrate, and a p-type doped layer formed on the n-type InSb layer. An InSb layer (absorption layer), a p-type AlInSb layer (barrier layer) formed on the p-type doped InSb layer, and a p-type InSb layer (contact) formed on the p-type AlInSb layer Layer).

  In the sensor element, the PIN photodiodes are connected in series by connection wiring. When infrared light is incident from the back side of the substrate (that is, opposite to the surface on which the PIN photodiode is formed), a photoelectromotive force corresponding to the amount of infrared radiation is generated in the PIN photodiode and passes through the connection wiring to form a sensor element. It is designed to be output outside of.

  A quantum sensor element operating at room temperature has higher sensitivity than a thermoelectromotive element such as a thermopile that is generally used conventionally, and the noise amount per signal, that is, the SN ratio is also better than those. In addition, the quantum sensor element can be formed into a shape that can be surface-mounted during assembly.

  FIG. 12 is a specific configuration diagram of a quantum sensor element used in Example 1 of the infrared sensor according to the present invention and each Example described later. The quantum sensor element 103 includes a sensor element portion 103a. The sensor element portion 103a includes a first contact layer 106 provided on the substrate 105 and an absorption layer provided on the first contact layer 106. 107, a barrier layer 108 provided on the absorption layer 107, a second contact layer 109 provided on the barrier layer 108, and a second element provided on the second contact layer 109 A partial electrode 111 b, a first contact layer 106, an absorption layer 107, a barrier layer 108, a passivation layer 110 provided adjacent to the second contact layer 109, and a substrate 105 provided via the passivation layer 110. The first element portion electrode 111a is provided. Note that the adhesive layer 112 and the optical filter 113 are not included in the sensor element portion 103a according to the present invention.

  That is, the entire sensor element portion 103a excluding the light receiving surface is covered with the mold resin 101, and sensor electrode terminals 102a and 102b for taking out sensor signals are provided on both sides of the sensor element portion 103a. Further, the pad electrodes 104a and 104b connected to the first element part electrode 111a and the second element part electrode 111b constituting the sensor element part 103a and formed on the substrate 105 are connected to the sensor electrode terminal 102a by wire bonding 115. , 102b.

  Further, the sensor element unit 103a will be described in more detail. For example, an n-type InSb contact layer 106, a π-type InSb absorption layer 107, a p-type AlInSb barrier layer 108, and a p-type InSb contact layer 109 are formed on a semi-insulating GaAs substrate 105, and the n-type InSb contact layer 109 is formed. The InSb contact layer 106 is electrically connected to one pad electrode 104a by the element part electrode 111a, and the p-type InSb contact layer 109 is electrically connected to the other pad electrode 104b by the second element part electrode 111b. Connected.

  The material of the semiconductor thin film that constitutes the sensor element portion 103a is not limited to the above-described example. In addition, the sensor element unit is not limited to the example configured with the above-described one set 103a, and the same may be applied even when a plurality of sets are connected in series or in parallel on the substrate.

<Example 2>
3 (a) to 3 (c) and FIGS. 4 (a) to 4 (d) are process diagrams for explaining Example 2 of the manufacturing method of the infrared sensor of the present invention.

  The manufacturing method of the infrared sensor 27 according to the second embodiment of the present invention is a manufacturing method of the infrared sensor 27 in which the optical filter 26 is formed on the light receiving surface 21 a of the sensor element 21, and the plurality of sensor elements 21 are separated by separating the wafer 20. The first dicing process for forming the sensor element 21 and the sensor element 21 separated by the first dicing process are mounted on the lead frame 22, and the sensor element 21 and the lead frame 22 molded by the resin 25 together with the wire 24 are individually provided. A second dicing step for singulation, and a filtering step for forming an optical filter 26 on the light receiving surface 21a of the sensor element 21 in the previous stage of the second dicing step. 25 is formed integrally.

  First, the wafer 20 is separated to form the sensor element 21 (FIG. 3A; first dicing step). Next, the sensor element 21 separated by the first dicing step is aligned in the recess 23 of the lead frame 22 and mounted so that the light receiving surface 21a of the sensor element 21 faces downward in the recess 23. (FIG. 3B; die bonding process). Next, the sensor element 21 and the lead frame 22 accommodated in the recess 23 by the die bonding process are accommodated and connected in the recess 23 by the wire 24 (FIG. 3C; wire bonding process).

  Next, the inside of the recess 23 is molded with the resin 25 except for the light receiving surface 21a of the sensor element 21 to which wire bonding is performed in this wire bonding process (FIG. 4A; molding process). Next, the mold body formed by the molding process is turned upside down, and the optical filter 26 is deposited on the surface of the resin 25 and the surface of the lead frame 22 including the light receiving surface 21a of the sensor element 21 (FIG. 4 ( b); Filtering step). Next, the sensor element 21, the lead frame 22, and the optical filter 26 molded with the resin 25 together with the wire 24 are separated into individual pieces (FIG. 4C; second dicing step).

  As described above, in the method of manufacturing the infrared sensor according to the second embodiment of the present invention, the optical filter 26 is attached to the surface of the resin 25 and the surface of the lead frame 22 via the adhesive in the previous stage of the second dicing process. The first dicing step as shown in FIG. 3A, the die bonding step as shown in FIG. 3B, the wire bonding step as shown in FIG. 3C, and FIG. After a molding process as shown in a), a filtering process as shown in FIG. 4B, and a second dicing process as shown in FIG. 4C, as shown in FIG. 4D. The infrared sensor 27 is completed. That is, in the infrared sensor 27 completed in the second embodiment, the optical filter 26 is attached over the entire surface of the resin 25 and the surface of the lead frame 22, and the light receiving surface 21 a of the sensor element 21 is interposed via the resin 25. An optical filter 26 is provided.

  In addition, the same optical filter in Example 2 as the optical filter in Example 1 mentioned above is used. Further, the same material as that used in the first embodiment is also used for the adhesive for attaching the optical filter 26 to the surface of the resin layer 25 and the surface of the lead frame 22. The sensor element 21 is preferably a quantum sensor element. Also for this quantum sensor element, the same one as in the first embodiment described above is used.

<Example 3>
Next, a quantum infrared gas concentration meter using the infrared sensor of the present invention will be described.
FIG. 5 is a diagram showing the sensitivity spectrum of the infrared sensor of the present invention. For example, an InSb-based quantum sensor element has a sensitivity band at an infrared wavelength of 1 μm to 8 μm. Typical gases having absorption in this zone include carbon dioxide, carbon monoxide, nitrogen oxides, sulfur oxides, formaldehyde and the like. FIG. 6 shows various gas infrared transmission spectra in the sensor sensitivity range. A quantum type infrared gas concentration meter can be realized by measuring the amount of infrared rays at the absorption wavelength using the infrared sensor manufactured in Example 1 and Example 2.

  FIG. 7 is a block diagram for explaining a quantum infrared gas concentration meter according to the present invention. This quantum infrared gas concentration meter is a one-light source / two-wavelength comparison NDIR gas concentration meter, and includes a quantum infrared sensor 32. The quantum infrared sensor 32 includes a plurality of quantum infrared sensor elements 33a and 33b. The plurality of optical filters 34a and 34b are provided on the infrared light source side with respect to the quantum infrared sensor elements 33a and 33b, and are different from each other. The optical filter 34b that selectively transmits infrared rays in a specific wavelength band, and has two wavelengths, that is, an optical filter 34b that matches the absorption characteristics of carbon dioxide and an optical filter 34a that transmits infrared rays having a wavelength of about 3.9 μm as reference light. The selected infrared rays are detected by the quantum infrared sensor elements 33a and 33b, respectively. In this case, a change with time of the output signal due to deterioration of the light source 30 or contamination of the sample cell 31 can be corrected by comparison with the measured absorption characteristic of the reference light.

That is, the quantum infrared gas concentration meter shown in FIG. 7 has the infrared light source 30 disposed at one end in the sample cell 31 constituting the flow path of the measurement target gas, and the other end in the sample cell 31 of the present invention. The quantum infrared sensor 32 is arranged, and for example, two wavelengths are selected by one filter that matches the absorption characteristic of carbon dioxide and the other filter that transmits infrared light having a wavelength as reference light. Are respectively detected by an infrared sensor. FIG. 8 is a diagram showing an example of CO ₂ concentration determination by the NDIR method of the present invention.

  Moreover, although the infrared sensor of Example 1 and 2 provided with the optical filter of each wavelength may each be arrange | positioned, as shown in FIG. 10, the sensor element of Example 1 is resin-molded integrally with 2 wavelengths. As a result, an infrared sensor can be realized that is small in size, has high sensitivity, and has a high-speed response, and that suppresses the temperature difference between the sensors and the difference in the amount of received light.

  As shown in FIG. 11, a quantum infrared gas concentration meter provided with four quantum infrared sensor elements and four optical filters can be realized. The four optical filters are composed of one optical filter for transmitting reference light from an infrared light source and three optical filters for transmitting wavelength bands different from the reference light, and measures the concentrations of three different gas types. be able to. If the sensor element of Example 1 is used, the infrared sensor which carried out resin molding by 1 body is realizable.

  When a plurality of sensors are integrally molded with resin, at least one of them may be without a filter for the purpose of monitoring the amount of infrared light.

  As described above, the configuration of the first, second, or third embodiment of the present invention has a small and simple sensor shape, and is stable against disturbance changes such as a change in the flow rate of the measurement gas and a change in temperature. It is possible to realize a quantum infrared sensor for a non-dispersive infrared gas concentration meter and a quantum infrared gas concentration meter using the same.

  The NDIR gas concentration meter of the present invention can determine the gas concentration of the gas to be measured by the following calculation. According to the Lambert-Beer law, the gas concentration c is expressed by the following equation when the incident light intensity Ig0 of the gas absorption band, the transmitted light intensity Ig of the gas absorption band, the absorbance coefficient ε, and the gas path length L are as follows. Can be represented.

  Since the incident light intensity Ig0 in the gas absorption band is proportional to the transmitted light intensity Ib in the wavelength band without absorption, if the proportionality coefficient is α,

  Therefore, using the amount of transmitted light in the gas absorption band and the amount of transmitted light in the wavelength band without gas absorption, the gas concentration can be determined by the following equation.

<Example 4>
Next, a human sensor using the infrared sensor of the present invention will be described.
FIG. 9 is a diagram illustrating an optical spectrum according to a difference in temperature of the heating element. Humans emit infrared rays of 4 μm to 20 μm with a peak of 10 μm. On the other hand, incandescent lamps installed on the ceiling of a room emit infrared rays having a peak near 1 μm. When an optical filter that transmits a wavelength longer than 5 μm is used, the influence of infrared rays caused by ambient light such as an incandescent lamp can be reduced, and a change in the amount of infrared rays by a human can be detected. As described above, by using the infrared sensor manufactured by the optical filter that transmits a wavelength longer than 5 μm according to Example 1 and Example 2, the malfunction is caused by disturbance light such as an incandescent lamp with small size, high sensitivity, and high speed response. It is possible to realize a small human sensor that suppresses the above.

<Example 5>
Next, a flame sensor using the infrared sensor of the present invention will be described.
The resonance emission spectrum of carbon dioxide in a flame has a peak at 4.3 μm, and it is known that a fire can be detected with high accuracy by comparing with the infrared intensity of a band for comparing other emission (for example, , See Patent Document 4).

  By using the optical filter of the corresponding wavelength using the infrared sensor manufactured according to Example 1 and Example 2, it is possible to realize a small flame sensor with a small size, high sensitivity, high speed response, and suppressed malfunction. .

<Example 6>
The manufacturing method of the infrared sensor 18 according to the sixth embodiment of the present invention is a manufacturing method of the infrared sensor 18 in which the optical filter 12 is formed on the light receiving surface 13a of the sensor element 13, and the wafer 10 with the optical filter 12 is separated. A first dicing process for forming a plurality of sensor elements 13, and the sensor elements 13 separated by the first dicing process are mounted on a lead frame 14, and the sensor elements 13 and leads molded with a resin 17 together with wires 16 A second dicing step for dividing the frame 14 into pieces, a filtering step for forming the optical filter 12 on the light receiving surface 13a of the sensor element 13 in the previous stage of the first dicing step, Adhesive layer (described later) formed avoiding the absorbing portion (reference numeral 114 in FIG. 13 described later) That has a sign 112) in FIG. 13, it is to directly integrally forming the optical filter 12 to the sensor element 13.

  Since the optical filter is attached through an adhesive layer formed avoiding the infrared absorbing portion, it has a small and simple sensor shape, eliminates infrared attenuation by the adhesive layer, changes the flow rate of the measurement gas, It can be stably measured against disturbance changes such as temperature changes.

  First, the wafer 10 is formed by attaching the optical filter 12 to the back surface of the wafer substrate 11 through an adhesive layer formed avoiding the infrared absorbing portion (FIG. 1A; filtering step). Next, the wafer 10 is separated to form a plurality of sensor elements 13 with optical filters 12 (FIG. 1A; first dicing step). Next, the sensor element 13 separated by the first dicing process is aligned in the recess 15 of the lead frame 14 and mounted so that the light receiving surface 13a of the sensor element 13 faces downward in the recess 15. (FIG. 1 (b); die bonding step). Next, the sensor element 13 and the lead frame 14 accommodated in the recess 15 by the die bonding process are accommodated and connected in the recess 15 by the wire 16 (FIG. 1C; wire bonding process).

  Next, the inside of the recess 15 is molded with the resin 17 except for the light receiving surface 13a of the sensor element 13 to which the wire bonding is performed in this wire bonding process (FIG. 2A; molding process). Next, the sensor element 13 and the lead frame 14 molded with the resin 17 together with the wire 16 are separated into individual pieces (FIG. 2B; second dicing step).

  Thus, in the infrared sensor manufacturing method according to the sixth embodiment of the present invention, the optical filter 12 is formed on the wafer substrate 11 through the adhesive layer formed so as to avoid the infrared absorbing portion in the previous stage of the first dicing process. 1 to be deposited, a filtering process and a first dicing process as shown in FIG. 1A, a die bonding process as shown in FIG. 1B, and a wire bond as shown in FIG. 1C. The infrared sensor 18 as shown in FIG. 2C is completed through the process, the molding process as shown in FIG. 2A, and the second dicing process as shown in FIG. In other words, in the infrared sensor 18 completed in the sixth embodiment, the optical filter 12 is directly provided only on the light receiving surface 13 a of the sensor element 13.

  The optical filter in the filtering process shown in FIG. 1A described above may be any filter having a function of selectively transmitting infrared light. As an example of this optical filter, an optical member and a thin film formed in multiple layers on this optical member have a function of not transmitting infrared rays having a long wavelength, a short wavelength, or both, and these As a result, the optical filter has a function of transmitting only infrared rays having a specific wavelength.

  The adhesive layer in the filtering step shown in FIG. 1A described above is formed avoiding the infrared absorption part of the sensor element because the adhesive has infrared absorption. The shape of the adhesive layer is, for example, simple to form on the ring only on the outer periphery of the substrate and easy to process.

  Since the adhesive strength between the wafer substrate 11 and the optical filter 12 is determined by the adhesive force per unit area of the adhesive, a minimum adhesive force is required to prevent separation after the post-process or completion. For example, when the shape of the adhesive layer is formed on the ring only on the outer periphery of the substrate, a sufficient adhesive area may not be ensured due to downsizing of the sensor element, and the adhesive strength may be insufficient.

  By using an adhesive layer on the sensor element other than the infrared absorbing portion, for example, on the pad electrode (reference numerals 104a and 104b in FIG. 12) (FIG. 13), the bonding ratio of the adhesive layer is increased to ensure the adhesive strength. can do.

  FIG. 13 is a top view for explaining the adhesive layer of the sensor element unit in the sixth embodiment. The adhesive layer 112 of the sensor element unit 103a is formed to avoid the infrared absorption unit 114 of the sensor element unit 103a, and an optical filter 113 is attached to the sensor element unit 103a via the adhesive layer 112.

  According to FIG. 13, for example, the substrate size is 0.7 mm × 0.7 mm, the width of the adhesive layer 112 on the outer peripheral portion is 30 μm, and two locations of 140 μm × 140 μm on the pad electrodes 104a and 104b are used as the adhesive layer 112. In this case, since the bonding area ratio of the adhesive layer 112 can be increased by about 50%, the adhesive strength can be improved by about 50%. At this time, the adhesive layer 112 on the outer peripheral portion may be connected to the adhesive layer 112 on the pad electrodes 104a and 104b.

  Further, since the adhesive layer 112 in the filtering step shown in FIG. 13 is formed so as to surround the sensor element portion 103a, the hollow portion inside is sealed. Due to gas exhaustion and absorption of the material forming the structure, pressurization and depressurization due to the processing process, pressurization and depressurization due to the operating environment temperature, etc., stress on the joint portion of the sensor element portion 103a and the adhesive layer 112 is caused. Problems such as fluctuations, lowering of adhesive strength and peeling may occur.

  FIGS. 14A and 14B are top views for explaining an embodiment in which a cutout portion is provided in the adhesive layer shown in FIG. 13, and FIG. 14A is an outer peripheral portion of the infrared absorbing portion 114. FIG. 14B shows the case where the notch 112a is provided at the corner portion of the adhesive layer on the outer peripheral portion.

  Thus, by providing the notch 112a in the adhesive layer 112 shown in FIG. 13, sealing can be prevented and stress on the sensor element part and the joint of the adhesive layer can be reduced. The notch 112a can be prevented from being biased in adhesive force by being diagonally formed with respect to the adhesive surface.

  Examples of the adhesive for attaching the optical filter 12 to the surface of the wafer substrate 11 include polyimide, polyethylene, epoxy, acrylic, and rubber. As a method for forming the adhesive layer, there are an optical method using a photosensitive material and a method of printing an adhesive on a necessary place. A method using a photosensitive material such as a photosensitive resin such as polyimide or BCB or a photosensitive rubber capable of stably forming a fine pattern is preferable.

  In addition, the optical filter in this Example 6 can use the same thing as the optical filter in Example 1 mentioned above. Also, the same sensor element 21 as in the first embodiment can be used. The sensor element 21 used in Example 6 is preferably a quantum sensor element. Also for this quantum sensor element, the same element as in the first embodiment can be used.

<Example 7>
The manufacturing method of the infrared sensor 27 according to the seventh embodiment of the present invention is a manufacturing method of the infrared sensor 27 in which the optical filter 26 is formed on the light receiving surface 21 a of the sensor element 21, and the plurality of sensor elements 21 are separated by separating the wafer 20. The first dicing process for forming the sensor element 21 and the sensor element 21 separated by the first dicing process are mounted on the lead frame 22, and the sensor element 21 and the lead frame 22 molded by the resin 25 together with the wire 24 are individually provided. The second dicing step to be separated and the filtering step of forming the optical filter 26 on the light receiving surface 21a of the sensor element 21 in the previous stage of the second dicing step, and this filtering step avoids the infrared absorbing portion of the sensor element. It has the formed adhesive layer (reference numeral 112 in FIG. The filter 26 is for integrally formed through resin 25.

  First, the wafer 20 is separated to form the sensor element 21 (FIG. 3A; first dicing step). Next, the sensor element 21 separated by the first dicing step is aligned in the recess 23 of the lead frame 22 and mounted so that the light receiving surface 21a of the sensor element 21 faces downward in the recess 23. (FIG. 3B; die bonding process). Next, the sensor element 21 and the lead frame 22 accommodated in the recess 23 by the die bonding process are accommodated and connected in the recess 23 by the wire 24 (FIG. 3C; wire bonding process).

  Next, the inside of the recess 23 is molded with the resin 25 except for the light receiving surface 21a of the sensor element 21 to which wire bonding is performed in this wire bonding process (FIG. 4A; molding process). Next, the mold body formed by the molding process is turned upside down, and the optical filter 26 is deposited on the surface of the resin 25 and the surface of the lead frame 22 including the light receiving surface 21a of the sensor element 21 (FIG. 4 ( b); Filtering step). Next, the sensor element 21, the lead frame 22, and the optical filter 26 molded with the resin 25 together with the wire 24 are separated into individual pieces (FIG. 4C; second dicing step).

  As described above, in the infrared sensor manufacturing method according to Example 7 of the present invention, the adhesive layer formed on the surface of the resin 25 and the surface of the lead frame 22 while avoiding the infrared absorbing portion is provided in the previous stage of the second dicing step. The optical filter 26 is attached via a first dicing step as shown in FIG. 3 (a), a die bonding step as shown in FIG. 3 (b), and as shown in FIG. 3 (c). Through the wire bonding process, the molding process as shown in FIG. 4A, the filtering process as shown in FIG. 4B, and the second dicing process as shown in FIG. The infrared sensor 27 as shown in 4 (d) is completed. That is, in the infrared sensor 27 completed according to the seventh embodiment, the optical filter 26 is attached over the entire surface of the resin 25 and the surface of the lead frame 22, and the light receiving surface 21 a of the sensor element 21 is interposed via the resin 25. An optical filter 26 is provided.

  FIG. 15 is a top view for explaining the adhesive layer of the sensor element unit in the seventh embodiment. The adhesive layer 112 in the filtering step shown in FIG. 4A described above is formed avoiding the infrared absorbing portion 114 of the sensor element because the adhesive absorbs infrared rays. The shape of the adhesive layer 112 is simple and easy to process on the ring, for example, around the light receiving surface 21a or only on the outer periphery of the infrared sensor separated by the second dicing process.

  Further, since the adhesive layer 112 in the filtering process shown in FIG. 15 described above is formed in a form surrounding, for example, the periphery of the light receiving surface 21a or the outer periphery of the infrared sensor separated by the second dicing process, The hollow part has a sealed structure. Due to gas exhaustion and absorption of the material forming the structure, pressurization and depressurization due to the processing process, pressurization and depressurization due to the operating environment temperature, etc., stress on the joint portion of the sensor element portion 103a and the adhesive layer 112 is caused. Problems such as fluctuations, lowering of adhesive strength and peeling may occur.

  By forming notches as shown in FIGS. 14A and 14B of Example 6 in the adhesive layer 112 described above, sealing is prevented and the sensor element portion 103a and the joint portion of the adhesive layer 112 are joined. Stress can be reduced. This notch part can prevent the bias of the adhesive force by putting it diagonally with respect to the adhesive surface.

  Examples of the adhesive for attaching the optical filter 26 to the surface of the resin layer 25 and the surface of the lead frame 22 include polyimide, polyethylene, epoxy, acrylic, and rubber. As a method for forming the adhesive layer, there are an optical method using a photosensitive material and a method of printing an adhesive on a necessary place. A method using a photosensitive material such as a photosensitive resin such as polyimide or BCB or a photosensitive rubber capable of stably forming a fine pattern is preferable.

  In addition, the same optical filter as the optical filter in Example 1 mentioned above can be used for the optical filter in this Example 7. FIG. Also, the same sensor element 21 as in the first embodiment can be used. The sensor element 21 used in Example 7 is desirably a quantum sensor element. Also for this quantum sensor element, the same element as in the first embodiment can be used.

10, 20 Wafer 11 Wafer substrate 12, 26 Optical filter 13, 21 Sensor element 13a, 21a Light receiving surface 14, 22 Lead frame 15, 23 Recess 16, 24 Wire 17, 25 Resin 18, 27 Infrared sensor 30 Infrared light source 31 Sample cell 32 Quantum type infrared sensor 33a, 33b Quantum type infrared sensor element 34a, 34b Optical filter 101 Mold resin 102a, 102b Sensor electrode terminal 103 Quantum type sensor element 103a Sensor element part 104a, 104b Pad electrode 105 Semi-insulating GaAs substrate 106 1st N-type InSb contact layer 107 π-type InSb absorption layer 108 p-type AlInSb barrier layer 109 second p-type InSb contact layer 110 passivation layer 111 a first element part electrode 111 b second element part electrode 12 adhesive layer 113 optical filter 114 infrared absorption portion 115 of wire bonding

Claims (4)

A plurality of quantum type sensor elements are formed on the entire surface of the second main surface of the wafer facing the first main surface of the wafer so as to avoid the infrared absorption part of the quantum type sensor elements. A filtering step of attaching an optical filter via an adhesive;
A first dicing step of separating the wafer to form a plurality of the quantum sensor elements;
The quantum type sensor elements, separated by the first dicing step, in a recess formed in the lead frame and the supporting substrate, a first main surface side of the wafer is exposed, the optical filter is the support A die-bonding process for mounting in contact with the substrate ;
A wire bonding step of accommodating and connecting the quantum sensor element formed on the first main surface of the wafer and the lead frame in the recess by a wire;
A molding step of molding at front Ki凹 portion except for the second optical filter surface formed on the main surface of the wafer resin,
A second dicing step of separating the quantum sensor element and the lead frame into pieces;
Are performed in this order, and the sensor element and the optical filter are integrally formed.   The lead frame has a stepped portion on a side surface of the lead frame forming the recess;
  2. The infrared sensor according to claim 1, wherein in the wire bonding step, the quantum type sensor element formed on the first main surface of the wafer and the stepped portion of the lead frame are housed and connected in the recess by a wire. Production method. Infrared sensor manufactured by the method for producing an infrared sensor according to claim 1 or 2. A quantum infrared gas characterized in that an infrared light source is arranged at one end in a sample cell constituting a flow path of a gas to be measured, and the infrared sensor according to claim 3 is arranged at the other end in the sample cell. Densitometer.

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